1. Field of the Invention
This invention relates to a plug cord connecting structure whereby a distributor and a spark plug or a distributor and an ignition coil are connected in an automobile engine compartment.
2. Prior Arts
A plug cord which connects a distributor and an ignition coil or a distributor and a spark plug of the engine in an automobile engine compartment plays an important role in leading a high voltage generated on the side of an ignition coil to the side of a distributor and a spark plug without a loss of voltage. Therefore, in a connecting structure used to connect a plug cord with a wiring terminal, there must be taken measures to prevent the displacement of a cord from a terminal and to prevent water from coming in when the engine compartment is washed, etc.
Conventionally, a plug cord connection is generally made by using a connecting cap made of a synthetic rubber superior in its electric insulating properties and waterproofness which is tightly fit over a tubular wall of a wiring terminal.
However, said construction only provides a single waterproof structure by fitting the connecting cap over the wiring terminal and is not sufficient in view of the waterproofness, so that further improvement in waterproofness has been desired.
Recently, there have been demands for reducing the space of the engine compartment and the size and weight of engine components, so that reductions in size and weight of the plug cord have also been desired. Accordingly, the cord diameter has been changed from the conventional 7 mm to 5 mm. If the plug cord diameter is changed to 5 mm, the wiring terminals of the distributor, ignition coil and spark plug also need to be changed to accommodate the 5 mm cord. However, this would enforce a change in all components in the ignition system of the engine.
Currently, not all components have been changed to accommodate the 5 mm cord, and only the plug cord connecting structure is changed as follows. That is, a connecting element of the plug cord is made to have a 5 mm diameter, and while the wiring terminal is maintained in the conventional configuration which accommodates the 7 mm plug cord, a terminal connecting element only is changed to accommodate the 5 mm cord. In addition, an insulation member of the plug cord connecting element is made of an elastic synthetic rubber material which tightly fits in the tubular wall of the wiring terminal in view of waterproofness. Further, as a countermeasure to prevent the displacement of the connecting element from the wiring terminal, a fixing cap made of a synthetic resin is placed over the insulation member and engaging holes of elastic engaging portion formed on the fixing cap are engaged and fixed with engaging pieces formed on the tubular wall of the wiring terminal.
However, this construction still provides only a single waterproof structure and is not sufficient in the waterproofness. Moreover, the fixing caps must be manufactured using different molds for each plug, because the locations of a cord outlet and an engaging portion formed on the cap vary depending on a lead-out direction of the plug cord, so that the connection structure using a fixing cap takes high manufacturing costs.
Furthermore, as the engaging pieces are formed on the tubular wall of the wiring terminal, a standard plug cord cannot be used as a substitute when exchanging the plug cord, and the same type of plug cord with a fixing cap must be used as a genuine plug. Therefore an inexpensive repair plug cord having high waterproofness has been desired.